Morphological and genetic diversity of Sarcocystis species parasitizing gulls (Larus) and corvids (Corvidae) in Lithuania

Members of the genus Sarcocystis are parasitic protozoa widespread in reptiles, birds, and mammals distinguished by a two-host prey-predator life cycle. Asexual multiplication with sarcocyst formation occurs in the intermediate host, while sexual stages develop in the small intestine of the definitive host. Previous studies have confirmed two species of Sarcocystis each in the muscles of gulls and corvids, but a greater diversity of these parasites is assumed in these hosts. The objective of this study was to determine the species richness of Sarcocystis parasites in muscle and intestine samples of Lithuanian gulls and corvids using morphological and molecular analysis. DNA sequence analysis revealed four morphologically indistinguishable Sarcocystis species in the muscle of Lithuanian gulls and three species – in the muscles of the investigated corvids. A new species of Sarcocystis, S. kutkienae, was described and confirmed in common raven, common magpie and hooded crow. The prevalence (p < 0.001) and density (p < 0.05) of Sarcocystis infection were reliably higher in the muscles of corvids than in the muscles of guls. During the study, S. columbae was identified for the first time in the muscles of gulls. For the first time, a pathogenic species S. halieti was identified in muscle samples of gulls and corvids. Also, during this study, for the first time, mixed Sarcocystis species infections were detected in the muscles of gulls and corvids. New intermediate hosts confirmed for five Sarcocystis species. For the first time, 11 Sarcocystis species were identified in the intestine mucosal scrapings of corvids